Combustor Heat Shield Carbon Avoidance via Air Momentum
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Solution Overview
Problem
Carbon residues build-up on the front face of combustor heat shields in small gas turbine engine combustors due to the close proximity of combustor liner walls and heat shields to fuel injectors, leading to engine performance issues and requiring regular maintenance.
Innovation Solution
A gas turbine engine combustor design with a heat shield featuring an air gap and localized airflow paths with impingement holes in the combustor shell aligned with carbon purge air holes in the heat shield, which provide enough air momentum to deflect fuel droplets away from the heat shield's front face, preventing carbon build-up.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If heat shields are mounted close to fuel injectors in small gas turbine engine combustors, then the combustor size is reduced, but carbon residues build-up on the front face of heat shields
Solution Approach 1:
The patent introduces a pneumatic system using carbon purge air holes and impingement holes to create high-velocity air jets that physically deflect fuel droplets away from the heat shield front face, preventing carbon deposition through fluid dynamic action
Solution Approach 2:
The patent applies localized airflow paths with impingement holes positioned at specific locations on the combustor shell where carbon build-up occurs, providing targeted protection only where needed rather than uniformly across the entire heat shield surface
2Volume of moving object
If heat shields are positioned close to combustor liner walls, then the combustor volume is minimized, but carbon residues accumulate requiring regular maintenance
Solution Approach 1:
The patent implements a self-cleaning mechanism where carbon purge air continuously flows through the air gap and impingement holes during engine operation, automatically preventing carbon accumulation and eliminating the need for manual maintenance interventions
Solution Approach 2:
The carbon purge air system operates continuously throughout engine operation, maintaining constant protection against carbon deposition rather than providing intermittent or periodic cleaning action
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively discourages carbon deposition on the heat shield's front face by using high-momentum air jets to divert fuel droplets, reducing maintenance needs and improving engine durability by minimizing carbon build-up.
Implementation Method 1
the impingement holes and the carbon purge air holes being sized to preserve enough air momentum at the exit of the purge air holes to deflect fuel droplets away from the front face of the heat shield
Implementation Method 2
aerodynamically pushing fuel droplets or rich fuel-air mixture away from a front face of the heat shield by jetting air out from the front face of the heat shield with enough momentum
Data Source
AI summary
The build-up of carbon deposition on the front face of a combustor heat shield is discouraged by jetting air out from the front face of the heat shield with sufficient momentum to push approaching fuel droplets or rich fuel-air mixture way from the heat shield.